We propose to continue our series of dissemination conferences aimed at prevention researchers. The topic of these dissemination conferences is methodology for longitudinal research. The conferences, called Summer Institutes on Longitudinal Methods, will be held annually in May from 2006 through 2010. The long-term objective of these conferences is to ensure that the field of prevention research maintains highest, state-of-the-art methodological standards. The proposed conferences will continue to contribute to this in two ways. First, they will help prevention researchers gain conceptual and practical understanding of advanced methodological and statistical procedures so that they can use these procedures in their research. Some of the cutting-edge methodological research to be disseminated at these conferences will originate from the NIDA-funded Center for Prevention Methodology. Second, the conferences will foster networking among prevention researchers who are interested in methodology and statistics, for the purpose of sustained mutual support and sharing of information. The conferences are to be held at the Penn State Conference Center, a modern and well appointed facility opened in 1994. Presenters are carefully selected for their expertise in statistical methods and their ability to offer an accurate, non-technical, and engaging workshop. The workshops incorporate computer exercises, so that the participants practice analyzing data and interpreting results. The atmosphere is work-focused but informal, with ample opportunity for questions and discussion. Interaction among participants and between participants and presenters is further facilitated by group lunches and a group dinner. A comprehensive set of materials is provided for later reference, including suggestions for additional reading and often including software. Support for attending the Summer Institutes is made available to minorities and early-career researchers. We have held similar dissemination conferences annually, with considerable success, since 1996 (with 1998-2005 funded by NIDA).